I was actualy looking at modding the neo3 dtb file just the other day. Found it had gone missing from the dts makefile . (arch/arm64/boot/dts/rockchip/Makefile)
--- Makefile.orig 2022-03-31 23:09:30.840184181 +0200
+++ Makefile 2022-03-31 23:14:43.734675836 +0200
@@ -25,6 +25,7 @@
dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3326-odroid-go2.dtb
dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3328-a1.dtb
dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3328-evb.dtb
+dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3328-nanopi-neo3-rev02.dtb
dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3328-nanopi-r2s.dtb
dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3328-rock64.dtb
dtb-$(CONFIG_ARCH_ROCKCHIP) += rk3328-rock-pi-e.dtb
